Digital Micro Spherical Focused Laterolog Tool (Digital EMSF) The Digital Micro Spherical Focused Laterolog Tool (Digital EMSF) is a resistivity logging tool. It applies to boreholes with water-base mud (Freshwater or saline water) and formation of sandstone or limestone. EMSF is developed based on the micro-lateral and proximity well-logging methods. Due to the special structure of the micro-spherical focused pad and mud cake corrected electrode, the effect of mud cake measurement can be eliminated effectively, and the resistivity log of flushed zone is more accurately. The Rxo curve and dH curve will be recorded at the same time during one run. When combined with the Digital Dual Laterolog Tool (EDLT), it will accurately evaluate the situation of penetrative formation and mud invasion, and therefore ascertain the nature of oil, gas and water content in the formation. The logging tool comes with a Pad Arm which is controlled mechanically, this enables the pad to close in to the borehole wall. With two optional pads, the tool can be applied to the borehole diameter 152-500mm. This tool can transmit and control digitized signal of micro resistance via ELIS Downhole Instrument Bus (EDIB). Because of it’s non-communicating inner EDIB, the tool will be place in the bottom of the logging array.